Safety wrench



Aqg. 7, 1945. A. L. PARKER SAFETY WRENCH Filed March 27, 1945 Patented Aug. 7, 1945 SAFETY WRENCH Arthur L. Parker, Cleveland, Ohio, assigninto-The Parker Appliance Company, Cleveland, Ohio, a

corporation of Ohio Application March 27, 1943, Serial No. 489,806

. Claims. ((181-177) The invention relates to new and useful improvements in a safety wrench adapted for use in turning bolts, nuts, and coupling elements or the like, hereinafter referred to as a part.

It is well known that by applying excessive pressure-to a wrench for turning a part, such as a bolt or nut, that often the threads are stripped, also that when excessive pressure is applied to the wrench for tightening a tube coupling, the end of the tube is pinched oi! within the coupling. Such unseen damage Jeopa expensive equip-- ment and'human lives. It is e purpose of the present invention to provide a safety wrench which is so constructed that the operator using the same will be warned when the pressure applied to the -wrench.is excessive and likely to damage the parts;

An object of the invention is to provide a safety wrench having a handle, a portion of which is grasped within the hand of the operator, which handle is so constructed that the operator through Figure 5 is a side view of a modified form of handle for the improved safety wrench.

Figure 6 is a side view of a further modified form of handle for the safety wrench.

The safety wrench embodying the invention includes a head i having a-socket 2 adapted to be attached to the part which is to be turned.

the feel of the hand will be warned when the pressure approaches an excessive pressure which might disrupt and injure the parts. 4

A further object of the invention is to provide a safety wrench of the above type,.where1n the handle portion grasped by the operator is so di- -mensioned that the portion thereof within the grip of the hand will flex underpressure, and thus the operator may determine through the feel of the hand the approximate pressure being applied to the wrench for the turning of the part to which it is attached.

Another object of the invention is to provide a safety wrench of the above type which is provided with means for varying the flexibility oi the.

portion of the handle within the grip of the hand of the operator, so that greater or less pressure is necessary for flexing the same to a given extent.

'rnese arid other objects will in part be obvious and will in part be hereinafter more fully dis- In the drawing. i Figure 1' is a plan view of a safety wrench embodying the improvements, also showing in broken lines the flexing of the handle when pressure is i applied for turning a part. 2 is a side view of the same; with parts of the head in section.

e 3 is a sectional view on the line A-Aof figure 2.

Figure 4 is a view of the head end of the wrench,"

similar to Figure 2, .but showing a modified means for Joining the handle to the wrenchhead.

There is an opening 8 leading to the socket so that the wrench can be conveniently applied to a coupling element associated with a tube'or pipe.

The socket head is shaped so as to provide surfaces conforming to the hexagonal shape of the nut 'to which it is to be applied so that when wall of which is a semi-circular recess 8 and in the other wall of which is a semi-circular recess 9. The head I of the safety wrench is slotted, as indicated at Iii, and mounted in said-head and extending across the slots are pins II and II. The handle may be detached from the head by turning the handle relative to the head so as to move the pins ii and i2 out of the recesses 8 and 8, respectively. The handle may then he moved lengthwise for disconnecting it from the head. a

'I'heslot I0 lies in the plane of the handle and this plane is parallel to the axis of the socket in the wrench head. Pressure is applied to the side face of the handle for the turnin of the part to which the wrench is attached, and this tuming torque is against the side walls of 'the slot.-

thickness at the wrench head to the outer end thereof. When the operator grasps the outer end portion of the handle and applies pressure thereto for turning the wrench the part to which it is attached, the handle will flex, as indicated in broken lines in Figure 1. It will 'be' apparent that the outer end portion of the handle which is of less thickness will flex to a greater extent than the'portion of the handle between the point I and the wrench head. This enables the operator through the feel of the hand and through. the extent of theflexing of the end of the wrench 2 a,sel,aae

' point adjacent the outer end 6 of the handle to a point near the head i and terminate in a recess II. These slots provide a tongue I. which is integral with the outer end of the handle and is free from connection with the handle at its inner end. Mounted on the handle are two flat rectangular plates i1 and is. These plates are connected by a U-shaped holding device I! which extends through the slots and are bent back onto the outer face of the lower plate. as shown in Figure 3, and thus the plates are caused to grip the handle and remain in a'flxed position thereon. These plates may be shifted along the tongue and wherever it is placed, it will limit the flex ing of the tongue so that the portion of the tongue between the plates and the outer end of the handle will flex with the handle, while the portion of the tongue between the plates and the wrench head will not be flexed, but will move out of the slot in the handle unrestrained. By-

the shifting of these plates along the handle the flexibility of the handle can be increased or decreased. when the plates are moved toward the outer end of the handle, then 'the flexibility of the handle between the plates and the wrench head is solely in the main handle. If these plates be shifted up close to the head, then to the pressure necessary to flex the handle is added a pressure necessary to flex the tongue it. When the wrench is to be used in connection with parts to be tightened whichwill stand a greater torque without damage, the plates will be shifted toward the wrench head and this will require a greater pressure before the handle will flex to an extent roughly indicated by the dotted lines in Figure 1.

While the exact pressure applied to the handle for tightening the part cannot be accurately and mathematically determined by the feel of the hand, yet an operator can determine approximately the'tightnessto which a part is turned and thus beassured that wrench pressure is not being applied to an extent to damage or weaken any of the parts.

In Figure 4 thewrench head I is of the same construction as shown in Figures 1 and 2. Likewise the handle 4 is of the same construction. The means for securing the handle to the wrench head is slightly dlflerent. Instead of providing a detachable connection as shown in Figures 1 and 2, the handle is secured between the walls of the wrench head by rivets or bolts ll, and

portionwithinthegraspofthehandwlllflex when pressure is applied to the wrench in the manner described in connection with Figures 1 and 2, and here again the operator will, through the feel of the hand, be able to determine the approximate pressure applied to the tightening of the part and therefore will avoid excessive wrench pressure which would be likely to damage th parts being tightened.

InFigure B,thewrenchhead l isofthe same construction as in Figures 1 and 2 and is secured rigidly and permanently to the handle 22 by means'of rivets or bolts i0, ii. In this form of the invention the handle 22 .is of uniform width from the wrenchhead to the outer end 28 and at the outer end is substantially semi-circular. The handle is'cut away as indicated at 24. The

recess formed by the cutting away of the handle is smaller at the inner end 2!, and larger at the outer end II. This will so dimension the metal of the handle that-the outer end portion grasped in the hand of the operator will flex when turning torque is applied to the wrench in the manner described in connection with Figures 1 and 2. This will enable the operator through .the feel of the hand to determine the approxi mate wrenchpressure which is applied to the turning of the part to which the wrench is attached and avoid excessive pressure which might damage the parts.

The handleis described above as detachably connected to the wrench head. This enables a, handle dimensioned for easy flexing to be removed and a substitute handle attached which is not so' easily flexed, where it is desired to use the wrench on parts to which a greater turning torque may be applied without injuring the same. It is obvious that many ways may be employed of detachably connecting the handle of the wrench head and only one simple means has been illustrated.

As previously stated, flexing or yielding of the I tests with this wrench indicate that even inexperlenced operators will invariably tighten parts to within a permissible range of tightness. Obviousiy, as a further precaution a: overtigh'tening and consequent damage to parts, the han- -dlecanbeconstructedsoastobreakorsnap in. two when the upp r limit of the rahge of pulous operators who fall to heed the warning given by the flexing of the handle within the thus the handle is rigidly and. permanently attached to the wrench head.

In Figure 5 the wrench head is of the construction shown'in Figures 1* and 2 and is athead to substantially the line H and from this line to the end of thehandle it tapers down to.

a relatively small end portion, as indicated 'at II. In view of this dimensioning of the handle so that it is of less width in the portion which is grasped by the hand of the operator, the end hand. a

It is obvious that many changes in the shaping of the parts and the dimensioning 'of the same may be made without departing from the spirit of the invention as set forth in the appended claims, It is essential, however, that the handle shall be of a'material which will be-flexed within thepressurenecessarytoturnanutorap t to which the wrench is attached to a proper degree of tightness. It is also essential that the flexto the wrench for the turnin of'the I claim;

1. A safety wrench comprising a head having means adapted for engagement with a part for turning the same, an operating handle rigidly connected to said head and extending outwardly therefrom, the outer end portion of the handle which is adapted to be grasped by the hand of the operator for turning the part being relatively wide and sufliciently thin as to flex within the hand of the operator when pressure is applied to the, handle for turning the part whereby the extent of flexibility of the portion grasped by the hand may be utilized for determining the approximate tightness of the part being tinned.

2. A safety wrench comprising a head means, adapted for engagement with .a part for turning the same-an operating handle rigidly connected to said head and extending outwardly therefrom, the outer end portion of the handle which is' adapted to be grasped by the hand of the operator for turning the part being relatively 'wide and sufficiently thin as to flex within the hand of the operator when pressure is apphed'to the handle forv turning the partand means for varying the flexibility of the handle, whereby the extent of flexibility of the portion grasped by the hand may be utilized for determining the approximate tightness of the part being turned.

3. A safety wreench comprising a head and a 7 means adapted for engagement with a part for turning the same, said head having a shank extending therefrom, an operating handle rigidly connected to said shank and extending outwardly therefrom, the outer end portion of the handle which is adapted to be grasped by the hand of the operator for turning the part being relatively wide and of spring metal and suiliciently thin as to flex within the hand of the operator when pressure is applied to the handle for-turningthe part whereby the extent of flexibility of the portion the handleso that the outer end portion of the handle which is adapted to be grasped by the hand of the operator for turning the part is sufllciently thin as to flex within the hand of the operator when pressure is applied to the handle for turning the same whereby the extent of flexibility of the portion grasped by the hand may be utilized for determining the approximate tightness of the part being turned.

5. A safety 'wrenchcomprising a head and a means adapted for engagement with a part for turningthe same, said head having a shank extending therefrom, an operating handle rigidly connected to said shank, said handle being of v spring metal relatively flat in cross section and having longitudinal slots therein forming a tongue which is integral with the handle at the outer end thereof and which is free of the handle at its inner end; means shiftable on the handle longitudinally of the tongue and engageable with the tongue for varying the flexibility of the handle, the outer end portion of the handle which is grasped by-the hand of the o'perator'being flexible whereby the extent of flexibility of the portion grasped by the hand may be utilized for determining the approximate tightness of the part being turned.'

ARTHUR L. PARKER. 

